bass blockers

Yes, add them, if it saves your speakers it is a good investment. Sounds like Teamrf needs to have a talk with the salespeople or recommend it himself. A pair of basic bass blockers are better than nothing if the deck does not have a crossover that will work with the built in amp. A pair of 200mf caps (non polar - mylar) would be the best bet for you, it is a approx a 200hz crossover with a 6db slope and goes in line on the positive lead to the speaker.

You will be saving your speakers from almost certain death. This is beacuse all of your speakers can play all frequencies, some (subs for example) play frequencies, like bass notes with much more force than that of 1 4" or 6x9" speaker. What happens is that the distortion coming out of the smaller speakers is masked by that of the more powerful subwoofer, then all of a sudden one day, no rear or front speaker.

The frequencies do not automatically disappear from the audio spectrum, they are rolled off. Most vehicles have a natural midbass hump around this area as well, it helps to fill in the void that is created. At the same time just because you have your crossover in the amp set at 80hz does not mean that the audio response has hit a brick wall and it stops, it too rolls off, usually at a higher rate than basic caps on your speakers. And yes they should be added to the front and rear speakers, what size are the speakers that you are using?

the front door speakers are pioneer ts-a1664 4ohm, rear deck speakers are pioneer ts-a6963 4ohm, and the subs are rf punch rfz3812 8ohm speakers.

by the way where can i purchase these capacitors cheap?